On Monday, FINA, the international governing body for swimming, enacted a new policy restricting transgender female athletes from competing against women in elite aquatics competitions.

For a transgender female to qualify for women’s events, the athlete must have transitioned before the age of 12 or not have undergone male puberty. Under these new guidelines, transgender swimmer Lia Thomas, who won the NCAA women’s 500 freestyle event earlier this year and who has voiced aspirations of competing in the 2024 Olympics, will no longer be able to compete in the women’s category.